Answer 1

Let `cos^(-1) (sqrt3/2) = y, " Then " cos y = sqrt3/2 = cos (pi/6)`

We know that the range of the principal value branch of cos⁻¹ is

`[0, pi] and cos (pi/6) = sqrt3/2`

Therefore the priciple value of `cos^(-1) (sqrt3/2) is pi/6`